Enclosed rolling mill



y 15, 1952 R. D. COLINET 2,603,114

ENCLOSED ROLLING MILL 7 Filed March 21, 1945 9 Sheets-Sheet 1 3 rwe/wtw"PE/-15 D. COL/HE T July 15, R952 R. D. COLINET 2,603,114

ENCLQSED ROLLING MILL Filed March 21, 1945 e Sheets-Sheet 2 n 0 PEN: DCO y 1952 R. D. COLINET 2,603,114

ENCLOSED ROLLING MILL.

Filed March 21, 1945 9 Sheets-Sheet 5 3 MW PENE D. COL /NET R. D.COLINET ENCLOSED ROLLING MILL.

Filed March 21', 1945 9 Sheets-Shet 4 RENE D. COL/NE T y 1952 R. D.COLlNET $603,114

ENCLOSED ROLLING MILL Filed March 21, 1945 9 Sheets-Sheet 6 FIE/5 LEE/YEDJC'QL/MFT J y 1952 R. D. COLINET 2,603,114

ENCLOSED ROLLING MILL.

Filed March 21, 1945 9 Sheets-Sheet s F/E. 25. M7

A pa /40 o v o 'N V EN TOR.

REP/ D. 604 mar July 15, 1952 R. D. COLINET ENCLOSED ROLLING MILL 9Sheets-Sheet 9 Filed March 21, 1945 &

INVENT FNBC0UN 7' BY W47: 1 I

Patented July 15, 1952 UNITED STATES PATENT OFFICE ENCLOSED ROLIJNG MILLRene D. Colinet, Philadelphia, Pa., assignor to La Soudure ElectriqueAutogene S. A., Brussels, Belgium, a Belgian company Application March21, 1945, Serial No. 583,887

2 Claims. 1

This application is a continuation-in-part of my copending applicationSerial No. 522,819, filed Februaryl'l, 1944, and now abandoned.

This invention relates to rolling mills of the type having formingrollers with cooperating spherical sealing surfaces and formingsurfaces. It is therefore an object of the invention to provide therollers with spherical sealing surfaces. A further object resides inprofiling the'rollers with forming surfaces to form a funnel in front ofor preceding the final restricted configuration of the shape to beproduced by the rollers.

Further objects will be apparent from the following description whenconsidered with the accompanying drawings which show a number ofpreferred forms of the invention and in which:

Figure 1 is a top plan view of an enclosed mill according to theinvention showing certain parts in section; 4

Fig. 2 is a vertical cross section of the mill of Fig. 1 taken on line 2-2 thereof V Fig. 3 is a horizontal section of the central portion ofthe mill taken on line 3-3 of Fig. '2;

Fig. 4 is a top plan view of a modified construc' tion;

Fig. 5 is a vertical section through the center of the cooperatingrollers taken on line 55 of Fig. 4;

Fig. 6 is a horizontal section of the central portion of the mill takenon line 6-6 of Fig. 5;

Fig. 7 is a top plan view partly in section of the mill of Fig. 4showing the drive connections;

Fig. 8 is a top plan view of another form of the invention for producingrectangularly-shaped bars;

Fig. 9 is a top plan view of a further modified mill for producingT-shaped bars;

Fig. 10 is a cross section of a portion of the rollers of Fig. 9 showingthe cooperating rollers merging into the T-shape configuration;

Figs. 11 to 15 are diagrams pertaining to comparative rigidity of partsof the rollers subjected to pressure or strain.

Fig. 16 is a horizontal section of four rollers showing an example ofnon-rubbing sealing surfaces obtained by replacement of pure sphericalsurfaces by torus or ellipsoid surfaces;

Fig. 17 is a vertical section of the mill of Fig. 16;

Fig. 18 is a horizontal section taken on line I-I of Fig.

Fig. 19 is a horizontal section takenon line II-II of Fig. 20;

Fig. 2.0 is a side view of the mill;

Fig. 21 is a vertical section through the center of the cooperatingrollers;

The invention is primarily directed to an improvement of the enclosedmill for use with hot or cold materials. By enclosed type is meant a?mill wherein the rollers are so formed as to contact each other in theplane of the axes,.leaving between them the shape of the product to beformed, which can be round, square, fiat, tubular or any other crosssection.

Whenever such enclosed rolling mill is used with a compressiblematerial, that is, onewhich 1 is soft or plastic enough to fiowlaterally when subjected to pressure, it is necessary to providef meansto oppose such lateral flow, and to direct the material closely and asdeeply as possible intoI the rollers. Otherwise, instead of reducing allof the material to the desired shape, the rollers may allowsome of thematerial to spread. laterally between them, and then would force thisexcess material into an edge or burr which would remain attached to thefinal product.

This difiiculty becomes even greater with fluid materials which aresupposed to solidify or coagulate in the rolling mill itself, such ashot liq uid metals, certain plastics, compressible powders,

quick-hardening pastes or mixtures, etc.

The means to oppose lateral fiowor-leakage between the rollers ahead oftheir contactplane,

as referred to above. are usually stationary wedges filling in all gapsbetween the-rollers. as far asthey can possibly go toward the contactplane of the rollers. Such wedges become exceedingly thin and fragile atthe very point where the pressure reaches its peak. Also they are unfitto withstand successfully both wear and heat action and they cannot beproperly cooled. In all cases, they must be interrupted ahead of thetangent point ofcontact of the rollers, leaving a narrow'gap unfilledbetween them. where lateral flow .canstill take place without restraint.

The provision of spherical sealing surfaces' on the rollers themselvesis designed to create supporting surfaces which oppose any-lateralfiow.

or leakage of the material, from a point far ahead of the contact planeof the rollers and where pressure is still non-existent or. at leastnegligible, to the very center of the rolling mill where the material isforced into its final shape or configuration. Such a mill forms a funnelbetween the rollers, the inside walls of which are leakproof, yet movetogether toward the smaller orifice in a converging manner, therebydragging the material along and forcing it through the outlet withoutany possible place of escape.

This result is obtained by assembling a number of rollers which, inaddition to the usual shaping surfaces which join in the center to formthe cross section of the final product, also have auxiliary surfaceswhich act as solid and tight walls all the way from a point aheadofwhere the material comes in contact with the rollers,'to a point beyondwhere the finished product leaves the rollers after being shaped. Toassure mutual contact between the rollers in all cross sectionsperpendicular to the direction of travel of the product, and not only inthe axes plane as it would be the case for the rollers of knownconstructions, the following geometrical conditions."

must be fulfilled: at least three rollers must be.

used, the axes of which intersect in at least two points at a finitedistance from the axis of the work; and any two adjacent rollers musthave a common surface of mutual contact which is a sphere, the center ofwhich is located at. the junction of their respective axes of rotation.It is desirable, though not necessary, that these axes belocated in thesame plane, but the'axes of adjacent rollers must always intersect. In afourroller mill, for instance, withaxes in different planes, the bightof. two rollers diagonally opposed is at a level different from that ofthe bightv of 'the'other two rollers. Therefore, the product I8 haveexactly the samedegree of curvature and the same diameter.

Figs. 4 to 7 illustrate an enclosed mill for producing round rods havingfour rollers 22, 23, 24 and 25 each rotatably mounted in a stationarybearing 25. Each roller has a head portion 21 and an integral shaft 28,and each head portion is provided with two spherical sealing surfaces29; and 30 and the annular forming surface 3 I. The two surfaces 29 and30 of each two adjacent roll-' ers cooperate with eachother so that, asshown in Fig. 6, the annular surfaces 2| merge into the roundconfiguration 32 from the trough-like funnel 33. All rollers revolve ateven speeds and in Y a converging manner.

Fig. 5 shows theliquid metal or plastic material 34 being poured from acrucible or container 35 into the funnel 33 formed by the head portions21 of the rollers. The rolled rod 36 emerges from the bottom of thefunnel after the revolving surfaces}! have profiled and formed thesolidifying material into the finished rod.

It must be observed that the spherical sealing surfaces have a slidingaction against each other. They do not roll like gears meshing together.Therefore, any foreign matter like spatter from liquid metal, or anymaterial particle that might adhere .to the surface of the roller wouldnot be pinched and flattened by the adjoining roller, but would becleared away by the edge of that roller, in scraper-like fashion. Thisassumes, of

w course, thatthe particle has not welded itself deep is first rolledone direction across its longitudinal axis, and then, a'littl'e laterbut in the same rolling operation, in the'direction perpen dicular tothe first one. This'method of successive rolling in cross directionslissimilar to the standard practice of hot rolling of round barsand rods,and may be preferred in some cases.' Rollers may, or may, not, beidentical.

Each roller is provided with two separate spherical sealing surfacesextending to the forming or shaping surfaces- Referringnow to thedrawings irrwhich like referencecharacters refer to corresponding parts,

throughout, Figs'l to 3, 9 and 10 showthreeroller mills and Figs..4 to 8show four-roller mills. Furthermore, the mill of Figs. 1 to 3 producesabar having a hexagonal configuration, Figs. 4 to '7, a roundconfiguration, Fig. 8a. rectangular configuration and Figs. 9 and 10 aT-shaped 6011-.

figuration- It is of course, obvious that any de-.

sired shapecan be produced as it is only necessary to appropriatelycontour theindividual rollers.

Theijmillof Figs. 1 to 3 has 'threecooperating rollers. ll, l 2 and J3eachrotatably mounted in a suitablebearing 14...,All three bearings areheld I rigidly in place by a sturdy. frame not shown in the drawings.Each roller is a duplicate of the othertwuandinclu'des a head portion l5with a shaft lfijshown as being integral for simplicity. Eachheadportion vI5 has two spherical sealing surfaces Hand 3, of which [-1is an end concave surface and I8 is an annular convex surface. Be-

tween these two spherical surfaces on each roller is the; annularforming surface I19 of which for the hexagon configuration each rollerwill impress two sides. All three rollers'are made to revolve aroundtheir respective'axes, atequal speedand in a converging direction.

Fig. 3 illustrates how the rollers merge as a into the roller by meltingit below its surface. For that reason, any liquid'steel being poured ina mill made of steel or iron rollers should never be overheated to suchextent that spatter from it would be hot enough to melt the rollerslocally.

' The rollers should be maintained as cool as possible throughartificial cooling, for instance by a water jet or spray underneath themill, directed toward the product and the rollers alike.

This sliding action of thenspherical sealing surfaces require thatadjacent rollers revolve smoothly against each other, withoutappreciable clearance, but also without excessive pressure. Play wouldallow leakage, while pressure would mean undue wear or abrasion. It ispreferable to 1 mild the rollers of a tough, wear-resisting material,such asa properly heat-treated tool steel,

also to grind them smoothly and exactly after heat treatment, and aboveall to secure enough rigidity in the bearings and theirsuppolting frameto eliminate relative motions under in-' ternal strain clue tocompression-of the material in the .mill. Means of fine adjustment ofthe bearings in all directions should be provided to bring the sphericalsurfaces in good contact, yet-' without excessive pressure, whenassembling the mill, and also compensating for possible-heat distortionby proper cooling, take-ups or releases, etc- Rollers should be easily-removable from their shafts, for quick change when worn or forreplacement ofdifferent shapes or sizes.

The rollers. are self-lapping, and the quality of their contact improveswith. usage. The

reason for this, is that the slidingaction, there-' fore the wear, isgreater at the periphery of each roller than it is near the annularforming. surface,

where the best contact is required because of." higher pressure. Atandnear the neck of. the.

mill, all. surfaces travel practically together,

parallelly and at the same speed, therefore with- The convexouterminimum friction and wear. spherical surfaces and the formingsurfacesare the only ones coming in contact with the material.

The concave central spherical surfaces never touch it. They shouldhowever be protected against'spatter or other stray particles by'the useof convenient guards.

As outlined above, it is obviously difficult to maintain the rollers ingood sealing contact, and yet to avoid at the same time pressure betweenthem. One method of overcoming this difliculty consists in a slightalteration of one or both of the sealing surfaces, so that they willcontact each other under relatively high pressure only in the regionclose to the center of the mill, where the relative motion of therollers is substantially a rolling action, exempt from sliding orpivoting friction. In all other regions where such sliding or pivotingoccurs, the sealing surfaces are no more in contact, but remain closeenough so that surface tension in case of liquids, and particle size incase of powder or fibres, will prevent any introduction of material inthe narrow gap between the sealing surfaces.

Fig. 16 shows by way of example how such result may be practicallyobtained. This figure is a horizontal section on the plane of the axesof the roller in a mill as shown in Fig. 4, while Fig. 1'7 is a verticalsection through the same mill on the axial plane of roller 23. Theinternal or concave surfaces 30 of all rollers remain unchanged. Theyare purely spherical with center 81 and" radius 31-98. By the externalor convex spherical surfaces 29 of all rollers have been replaced bytorus surfaces. One of them'is defined by a portion of circle of radius99IIIB and center 99 rotating around axis BL-HII while remaining rigidlyattached to that axis. .In the position shown, center 99 is on astraight line with 81 and the center of the mill, and at such distancefrom. axis 8I-IIII as defined by the quantity: clearance/ /21). Byclearance is meant the distance considered desirable between therollers, measured as I03--I04 on axis 87-81 of roller 23. In case ofsteel casting, a fair and satisfactory value of the clearance is & inchto inch.

From the vertical section, Fig. 17, it can readily be seen that theclearance is constant in each vertical section parallel to axis 81-87,although it gets smaller from one vertical plane to another whenapproaching the center of the mill. This is as it should be, since thepressure exerted by the rollers on the material increases toward thatregion, and also because the relative motion of rollers 23 and 24becomes more and more a slideless rolling nearer to the center of themill. Near the very center, positive contact is obtained between therollers which can now be actually pressed hard against each other. Theywill not separate, regardless of the flexibility of the bearings andtheir supporting frames, as long as the operating pressure on theproduct remains inferior to the pre-set pressure put on the rollersduring assembly.

A similar result would be obtained, either by the use of an ellipsoid ofrevolution defined by an ellipse rotating around its longer axis 8I-IOI,or by'a roller having a narrow portion of spherical sealing surface,adjacent to the forming grooved surface, and followed by a widerspherical quasi-sealing surface of same center, but with a slightlyreduced radius.

It is obvious that theshafts of the rollers can be driven by anysuitable means. Preferably, all rollers should be power-driven at equalperipheral speed, measured on the annular forming surface. Sometimes,however, idler rollers are acceptable, as in Fig. 8. Fig. 7 illustrates6 various details of one way for driving the rollers 22 to 25. As shown,the main shaft 3'! is driven by any suitable means such as a motor, notshown. Two sprocket wheels or pulleys 38 and 39, bevel gear 40 andpinion M are mounted to. rotate with and on the shaft 31. Sprocketwheel. or pulley 38 drives a chain or belt 42 which in turn drives asprocket wheel or pulley 43, the latter being mounted to rotate-theshaft of the roller 23. Also sprocket wheel or pulley 39 drives a chainor belt 44 which drives a sprocket wheel or pulley 45. This wheel 45drives the shaft of the roller 24 through the intermediary of bevelgears 46 and 41 and shaft 48. Bevel gear 4|] meshes with a bevel gear 49secured on the shaft of the roller 22. Pinion 4I drives another pinion59 secured on the shaft of the roller 25. All drives are proportioned toinsure equal speed of rotation for all four rollers. As shown in Fig. 7the shaft 31 rotates in the direction of the arrow which will impart adirection of motion to each of the rollers as indicated by the arrows sothat they shall all rotate toward the funnel and forming center for thebar to be produced. An-

other way, shown in Figs. 23 and 24, of driving the rollers wouldinvolve four auxiliary shafts forming a square around the mill,connected;

together through bevel or spiral gears. Each one of these shafts, inturn, would operate its corresponding roller, through a chain drive or apair of spur gears.

A particularly preferred form of mill frame consists in a number ofpanels, equal to the number of rolls, which arehinged to each other likea multiple panel door. Each panel holds one roll, its bearings, driveand accessories. To

open the mill, for inspection, cleaning or rollchanging purposes, it isonly necessary to remove one of the hinge-pins and to spread the panelsopen, without losing in that operation any of the fine adjustments whichhave been made to bring the rolls in proper contact with each other in aprevious assembling. Fig. 23 illustrates this design in the case of afour-roll mill,

shownclosed and ready for operation. Fig. 24 represents the same mill asopened for inspection. One of the panels, marked I33 in Fig. 24, isrigidly afiixed to the basejl34. Its shaft I35 extends backwards whereit is driven'byamotor, not shown, preferably through, a speed variator.The corresponding roll I36 is operated by a chain drive I31. That sameshaft I35 holds two spiral gears I38 and I39, which will mesh at degreeswith similar gears on the other panels, when the frame closes. relativedisplacements of the shafts as long as they remain at right angles. Whenin mesh,

all four rolls revolve together at identical speeds,

from the outside drive on shaft I35, through the spiral gears, the othershafts and the chain drives.

A further improvement consists in using hingepins which are eccentric indesign, and which are interconnected so as to rotate with equal Thistype of gears permit slight to move only at right angle to the roll axisof permits to use various sets of rolls 'with slightly differentdiameters, provided all rolls'in each particular set remain identical insize. Such would be the case, practically, for rolls'which have beenre-dressed after wear. Re-dressing a set of :rolls consists in machiningor grinding alloutside convex sealing surfaces to a diameter slightlysmaller than the original one, and doing the same to the inside concavesurfaces; Since the inside concave sealing surfaces must be res duced*in diameter to the same extent as the convex ones, the re-dressingoperation requires of necessity a transfer of the centers of'thesealing. surfaces toward the shaft end of each roll.

Reedressing. while keeping the centers where originally located wouldwrongly result in a reduction of the diameter of the convex surfaces,and an increase of diameter for the concave surfaces, destroying thegood mating of adjacent rolls. The displacement of the centers in eachsuccessive-re-dressing depends on the depth of metal to remove from thesealing surfaces, and should best be determined from a full-size drawing. The distances between both centers (convex and concave sealingsurfaces) of each roll are also reduced in a re-dressing operation, inproportion with the reduction of diameters. Therefore,xthe polygon ofthe rolls axes in the mill also becomes smaller with each re-dressing,al-

through this polygon remains unchanged in shape or symmetry.

The panel-type mill frame, with its inter-related eccentric hinge-pins,precisely provides for such contraction of the polygon of the axes, and

Theform or configuration of the bar produced in the mill shown in Fig. 8isindicateda ttf65f-v which shows the actual forming or pressing contour for the work as confined by'the surfaces '5l' and60.

The mill of Figs. 9 and 10 is designed to produce. a profiled bar ofapproximately T shape; I mill has a main roller 66 rotatably mounted inbearings 61 by means of a drive shaft or shafts 68. Two auxiliaryrollers 69 and 70 are rotatablymounted in bearings H and 12 respectivelyby means of drive shafts I3 and 14 respectively. The roller 66 hasannular forming surfaces 15 and; annular spherical sealing surfaces 16and" one. on each side of the surfaces 15. The roller 69 has an endspherical sealing surface ,18 and annular] forming surfaces 19.. Theroller lfl'also halsia I similar end spherical sealing surface 80andfs'imilar annular forming surfaces 8 I. 1 Roller 10 "how ever has anintegral annular abutment flange 82 of which the side or forming surface83 abuts and contacts a side surface84 of roller 69; All three rollersare made to revolve at substantially equal peripheral speeds. Fig. 10shows the ultimate .T i shape 85 produced by the merging surfaces 15 and19 together with surface 83. i In Fig. 1 the axes of adjacent rollers IIto [3 intersect in points 86 which are also the centers of the sphericalsurfaces l1 and I8. Theshapin'glf surfaces [9 are surfaces of revolutiongenerated by a portion of the cross section of the product revolvingaround the axis of the'corre'spondin'g roller. In Figs. 4 and '7 theaxes of adjacent rollers 22 to 25 intersect in points 81 which are thecentersof the spherical surfaces 29 and 30. In Fig. .8 the axesintersect in points 88 which are'the centers of the spherical surfaces55, 56, 58 and 59.

If and when the axes of two adjacent rollers are parallel as axes 89 inFig. 9, their correspond- *ing point of intersection is at infinity andthe fl'i common spherical surface becomes a plane'surface 83 and 84perpendicular to these axes 89.

The points 90 are spaced and accessible but the accommodates for anumber of sets of rolls, differas other int is at infinity. The exactradius of the ing in dimensions from set to set, but not within Sphere;or the exact location of e pla e when Y each set. No modification isrequired to the fine the Point of intersection 18.31? infinity; is l dadjustment originally made'to positi th first by the geometricalcondition that the sphere or set of rolls correctly in the mill. 7 Thesimplified Plane 5 contain the. point whelewhelshagping procedure tochange rolls includes the-following surfaces of the correspQnding r t nsteps: first, release all roll pressure by moving all Plane of the theserollels- ,FQ instance. panels awayfrom center, through a single drive In61 the Spherical s. 1' 5 Co ain lever or-crank; then remove one "of thehinge-pins point 9! Where forming aceil' Of roller 23 v and spread thepanels open. Unfasten all rolls meets forming Surface 3 of er 2- andfasten the rolls of the new set. Close the At h j o of e annular formingu face panels re-engage thehinge;pj n.and apply pres; With the sphericalsealing surfaces the rollers surethrough th leverer k. 1 present a sharpedge. The mechanical strength In th forms of. the in ho n in Figs, 1 t 7of that edge under pressure or strain from the all of the rollers ofeach mill are identical as to compressed r can be measured by the n sizeand shape. It is; however, possible to have a between he fi sl bothprofiles meefiiilg it V the edge considered. In Fig; 3,'such angle wouldbe 929l- 93 for one edge, and 92 9I 9'4 for the other edge. Forconstructive reasons, it is obvious that these angles should be aslarge'as different sizes and shapes of forming-rollers'in' the mill as,for instance, shown in Fig. 8 which has two larges rollers 5| and 52 andtwo smaller rollers 53 and 54. Each of the rollers '5l'and 52 has twospherical sealing surfaces 55 and 56 with (is possible, and inno casesmaller than 30 deg. for

a cylindrical surface 51 between "the two. Each of the rollers 53 and 54has two" side spherical sealing surfaces 58- and 59 and a cylindricalperipheral surface 605- Suitable shafts 6|, '63 and 64 drive and rotatethe respective rollers 5!, 53 7 0 desired shape of the product. .Athree-roller mm} and 54 in directions indicated by the arrows and isparticularly well adapted for hexagon shapes... at substantially equalperipheral speed, while rolbecause, as Fig. 3 shows, angle92'9|-9'31s"90 ler 52 revolves as an idleraround stationary deg. whileangle-92 9 9 is 5 s shaft .62 which is eye-shaped at the ends to per--mit passage of shafts 63 and 6d; 1

soft compressed materials'and 45 deg. for hard materials, with preferredvalues at or above deg. This condition will bea decisive factor inthe'choice of'the number of rollers with respect to the; 4 I

three-roller mill, however, would not be recom-. mended for a circularshaped product because. as;

9 Fig. 11 shows, angle 92-9l-93 would'be only 30 deg. Figs. 12, 13 and14 indicate'that this angle for a circular shape becomes 45 deg. for afour-roller mill, 54 deg. for a five-roller mill, and Y 95-96-91,forwhich a preferred value would be 30 deg., thus obtaining 60 deg., 75deg.,"84;deg.. and 90 deg. for 3, 4, 5, and 6 rollers respectively.

This alteration of the circular shape has another important function,which becomes apparent in Figs. 18 and 19 showing therollers, first whencompletely closed h in the center of the mill; second, after they havestarted to disengage themselves from the rolled product-a littlebelowcenter. It will be noted that opposite rollers move outwardly andparallelly as indicated by the arrows N11. The plane surface 9I-95 ineach roller, therefore, moves in its own plane, forcing the product torotate clockwise as shown by arrow I08. In that motion, the excessmaterial of the triangle 9l-95-I05 in Fig. 18 is rolled downtransversely to the correct circular shape l-l06 in Fig. 19.

The advantages of this design are self -evident: a perfectly circularshaped product is obtainable although the rollers are given anon-circular shape at the bight, in a view'to' reinforce the mechanicalstrength of their edges. Another advantage is that the product ispositively guided out of the mill by parallel planes. It will thereforebe delivered perfectly straight and could not adhere to any roller inparticular.

The rotation of the product combined with the longitudinal motion of thewire, result in a continuous twisting or helical motion of the product.Such motion may either be neutralized, or it may be preserved.

In the first case, it will only be necessary to reel the. product in astationary reeling device, and the wire will untwist itself afterleaving the mill, while still in a plastic stage. In the second case,-the twist can be preserved all along;the product by giving the reelingdevice a continuous rotation around the axis of the wire or rod, in suchdirection and at such speed as to correspond to the rotation of the rodshown by arrow I08. Any burr or marking will then appear as a helix allalong the wire which is a decisive advantage when subsequent colddrawing operations are involved, because of a more even wear of thedies.

Figs. 3, 6 and actually illustrate the fun nel created by the formingsurfaces of the rollers. There are no open gaps in the funnel and thusno leakage of metal or plastic when used in the fluid state. It is notonly possible to use the mills for metals in molten, hot or cold statebut for quick-setting fluids and substances or plastics as well as forcompressing fibers or powders. The products produced by the mills are inthe shape of bars and slabs of any rollable cross section and indefinitelength.

When used with hot liquid metal or alloy, these mills can operate eitheras a continuous mould, or casting machine, Or as a regular rolling mill.In the first case, the metal would be permitted to cool just enough toacquire sufficient cohesion to hold itself together in bar form underthe mill, where it would be cooled subsequently by water spray orotherwise. Very little pressure would be imposed on the machine 7 inthat case, ensuring'little wear and low power consumption In the secondcase, the cooling would be more pronounced, and thematerial would comeout under appreciable side pressure from the rollers. Some pre-cooling.could be provided also by provision of, a refractory tube standing abovethe mill and shaped at the bottom to contact the ;r'ollers withoutexcessive clearancej In such a" case, 'hotmetal poured in the tube wouldsetor solidify. partly in hot ingot form which, in turn; would be workedby the mill and rolled tothe final shape. This process could becontinuous, the ingot beingfed at the top while dropping steadilytowardthe mill. Any of the above-mentioned products could bere rolled orotl'l'erwiseitreated.

I Means of feeding hot metal'iat,constant level, either in the millitself, or. in the ltubeyshould be provided. .With light-emitting. fluidmetals, like steel, photoelectric devices could maintain a correct flow,while pyrom'etricv ormec'hanical feelers would operate better on, darkmetals like lead or other low: melting alloys and for'fpastes orplastics." The mills, can also be used-as frictionless outlet dies forextruding presses, being either power-driven or idle, with or withoutthe usual central core or I mandrel for tubular or hollow shapes or for.covered wire, cables and welding electrodes? sheathed with a protectivet n 1 Ladles with abottom -pouring nozzle arepreferred because of thelengthjof the jet. of liquid metal, measured between the nozzle and thespherical rolls,'can beheld short andv vertical regardless of the sizeof the ladle. Also, such jet will respond immediately to any motion ofthe stopper, in incr,ease. or decrease of the out put, under control of.photoelectric or'other devices depending upon the levelgof the liquidbath between the rolls of the mill,

Greater steadiness. and. stability of thatjlevel can be achieved if theservo-motor acting on the stopper of a bottom-pouring ladle, or on thetilting of a top-pouring ladle,.is.made to be sensitive, not only to thelevelof liquid metal between the rolls but also to the firstderivativeof thatjfu'nction, namely the speed by which such level rises or lowers.In casesof extreme inertia (heavy ladle of the tilting-type) it may be,indicated to. render the servo-motor sensitive also to the sec-' ondderivative of the level function, namely the rate of acceleration ordeceleration of its variation or, in other words, the variation of thespeed by which such level changes. This method is highly effective inthe prevention of hunting around the position of ideal equilibrium, andin reducing the magnitude of the deviations from the optimum level.

Figure 21 shows a photo-electric control system for a tilting ladle,also adaptable to a bottompouring ladle or furnace. The ladle 35 ishinged at the lip I09 and its bottom is raised by a cable I l 0 pulledby a winch l H driven by one or more electric motors H2. Aphoto-electric cell H3, fitted with a cone-shaped visor H4, receives thelight emitted by the bath of molten steel H5 laying between the rolls ofthe mill. The higher the level of that bath, the wider the bath, themore light emitted and the greater the current generated by the cell.This current is amplified and automatically analyzed as shown in Fig.22, by way of example only. Three direct current electric motors H6, H1and H8 are used, all mechanically coupled to the same shaft H2 in Fig.21. All three have independent magnetic ,etficient of self-induction.

racoau-r the com bined torque of all threermotors acting onwinch III.

The current generated by photo-cell I I3 is first amplifiedbya triode H9and then sent through a. Wheatstone bridge, I20 before energizing motorIIB. All four branches of the bridge have equal ohmic resistance, buttwoof them, I22 and I23, are strictly non-inductive resistors, .while .the

other two I24 and I25 are coils witha-high co- The armature of motor II6 is connected between the junction point of bridge I20 andresistor I2I,and anad- 'justablecontact I26 on potentiometer I21. .This

contact isepositionedto nullify the .voltage applied to motor II6whenthe level of bath Iliis normal. Iheladle 35 will be raised andthefiow of metal 34 increased if the .level is subnormah or the ladlewill be lowered and the vflow decreased if the level is over-normalwith,however, a double corrective action from 'motors- II I and H3.

Motor H1 is connected, through amplifying triode I28, to junctionsvI23-.-I24 and I22-I25 of the bridge I20. These points are at equalvoltage for any current emitted by triode I I9,,as long as that currentdoes not vary. But if it does, the retarding effect of coils I24 and 125results in a temporary unbalance of bridge I20. Motor -I I! will tend toincrease the metal flow 34 when the .bath H is going down, regardless ofits position. inversely, it will tend toreduce the flow when the levelis going up.. Similarly, motor H8 is made sensitive to the variationonly of the current emitted by triode I28, by the use of a. triode I3Iand a second Wheatstone bridge I32 identical to the first one. Thismotor II 8 will tend to increase the flow of metal 34 when the downwardspeed of the level H5 is increasing, or the upward speed decreasing. Itwill reduce that flow if the downward speed of the level decreases, orthe upward speed increases. In order to render bothmotors II! and H8.responsive to positive as well as negative unbalance of bridges I20 andI32, despite the unidirectional properties of triodes, some compensatingdevice must be used, ifor instance a polarizing battery I29 in the gridof triode I28, the effect of which is exactly compensated when thebridge I20 is balanced,

- through another. polarizing battery I 30 shunting M-rnotorII'I. H

.. .I claim .as my inventioni 1. :A rolling mill comprising at leastthree rollerseach rotatably mountedin sealing, contact swithone anotherhavingsealing and forming surfaces and all rotating -atsubstantiallyequal peripheral speed in a converging directiom-said rollers: havingtheir axes of revolution in-a c'oinrnontplane. and QImin a funnel-shapedo'penin'g closed on all sides; each rollerhavinga. concave sealingsurface of revolution closely-enveloping ,a corresponding convexsealingsurface of r'ev'olu- ..tion of the adjacent roller, and said twosurfaces intersecting the plane of the axes of the rolle'rs:alongtwodistinct curves tangent to each other where they. join theforming'profile of'the rollers and then extending outwardly in' closeconform- .ity, but progressively'divergingslightlyfrorn' each other. 1

.2. .A .rolling mill comprising. at least three rollerseach rotatablymounted in'sealin'g contact with oneanother and all rotating atsubstantially equal peripheral speed in a converging'direction,

'eachroller having a concave sealing surface'of .revolution closelyenveloping a corresponding convex sealing torus surface on the adjacentroller, said two vsurfacesintersecting the plane of the axes of therollers respectively along'a curve and a circle tangent to each otherwhere they join the forming profile of the rollers, and then extendingoutwardly in close conformityjbut pro gressively diverging slightly fromeach other.

-. RENE ncoLI'NE'r.

REFERENCES CITED The following references are of record in the file ofthis patent: 1

UNITED STATES PATENTS

